This question doesn't really make a lot of sense. The source string you've quoted is 13 characters long and doesn't have any "u"s in it at all; did you mean var source = "\\u5c07\\u63a2\\u8a0e HTML5 \\u53ca\\u5176\\u4ed6";? What's your actual underlying technical problem? The real source data, and the real desired end result?
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T.J. CrowderJun 19 '11 at 5:50

I think you are misunderstanding the purpose of Unicode escape sequences.

var source = "\u5c07\u63a2\u8a0e HTML5 \u53ca\u5176\u4ed6";

JavaScript strings are always Unicode (each code unit is a 16 bit UTF-16 encoded value.) The purpose of the escapes is to allow you to describe values that are unsupported by the encoding used to save the source file (e.g. the HTML page or .JS file is encoded as ISO-8859-1) or to overcome things like keyboard limitations. This is no different to using \n to indicate a linefeed code point.

The above string ("將探討 HTML5 及其他") is made up of the values 5c07 63a2 8a0e 0020 0048 0054 004d 004c 0035 0020 53ca 5176 4ed6 whether you write the sequence as a literal or in escape sequences.